President Barack Obama delivers his State of the Union address to a joint session of Congress on Jan. 20, 2015, as Vice President Joe Biden applauds and House Speaker John Boehner of Ohio listens. (Associated Press) more >

President Obama’s long and boastful goodbye to the nation begins Tuesday night with his final State of the Union address.

Departing from tradition, Mr. Obama plans to use the annual speech to set a course for his successor to build on his legacy, rather than to implore the disapproving Republican majorities in Congress to work on his dead-on-arrival liberal priorities this year. That process will start by laying out familiar themes, such as gun control and climate change, that can benefit Democratic presidential front-runner Hillary Clinton.

“This is not just about the State of the Union; it’s about the state of Hillary Clinton’s campaign,” said Robert Lehrman, a public communications professor at American University and former speechwriter for Vice President Al Gore. “Despite what you hear about friction between the two of them, there’s no question it’s tremendously important that he can help in whatever way he can.”

The 9 p.m. address will be one of the president’s last opportunities, barring another crisis on a level with San Bernardino, to speak to a broad national audience on live TV. It’s also Mr. Obama’s last moment in the prime-time spotlight before voters begin to choose the next president, starting with the Iowa caucuses Feb. 1.

“We’re going to move to a completely different dialogue in the next three weeks,” said Norman Ornstein, a political analyst at the American Enterprise Institute. “Once you hit the Iowa caucuses, the entire conversation is going to shift to the horse race and to the rhetoric of presidential candidates. The focus turns away from the president.”

White House officials have been previewing themes that Mr. Obama intends to hit in his speech, and his message to the nation could be summed up this way: I’ve brought you this far. Don’t blow it.

White House press secretary Josh Earnest said Monday that the president sees the address “as an opportunity to talk to the country bluntly about the challenges that we face and the opportunities that are there for the taking.”

“No country in the world is better positioned to capitalize on those opportunities [than] the United States,” Mr. Earnest said. “And that ultimately is the essence of the message the president wants to deliver, precisely because the next president needs to understand that and the American people need to understand that.”

Many interest groups call on the president each year to push their agendas in his speech, but one of the most likely to strike a chord this year is a letter from the Council on American-Islamic Relations, the nation’s largest Muslim civil rights and advocacy group, which urges Mr. Obama to offer support for the American Muslim community.

CAIR National Executive Director Nihad Awad called on the president “to offer a strong defense of our nation’s long-standing traditions of religious inclusion and mutual respect at a time when the forces of division and polarization seem to dominate.”

The president has practical reasons, too, to look beyond this year. In addition to his inability to work with Republicans in Congress, he has a job approval rating that averages about 45 percent.

Most public opinion surveys show that more than two-thirds of voters believe the country is on the wrong track.

Mr. Earnest blamed part of the president’s poor showing in polls on “the avalanche of negativity that we have seen from the Republican candidates for president.”

“The willingness of those candidates to exploit people’s fears and insecurities and anxieties has infected the political debate,” Mr. Earnest said. “That’s surely part of it.”

He also said many Americans are “feeling insecure about the economy,” and in the wake of the terrorist attack in San Bernardino, California, in December, “people are understandably concerned about national security.”

House Majority Leader Kevin McCarthy, California Republican, said it is “baffling” that Mr. Obama will use part of his speech to trumpet his foreign policy leadership. He pointed to the rise of the Islamic State in Syria, Iraq and Afghanistan, North Korea’s testing of a nuclear weapon, and Iran’s sponsorship of terrorism even as it violates U.N. Security Council resolutions on ballistic missile testing as evidence of a failed foreign policy.

“If he truly thinks we have a winning foreign policy, the president’s machinations are ignorant, bordering on delusional,” Mr. McCarthy wrote in an op-ed in USA Today. “America’s voice and more importantly, actions, are largely dismissed abroad. Foreign aggressors have taken this era of American weakness to do as they please, which has resulted in a more dangerous and anarchic international system.”

On the domestic side, Mr. Obama can point to achievements including an unemployment rate of 5 percent, down from 10.2 percent in the depths of the recession in 2009, a resurgent auto industry and increased output of clean energy.

He will likely call for cooperation from Congress on at least two legislative objectives: criminal justice reform and approval of the Trans-Pacific Partnership free trade pact.

If he chooses to be blunt, the president might delve into the nation’s bitter partisan divide, which he came into office promising to mend. He could address persistent social strife that has given rise during his watch to movements such as Black Lives Matter.

“I’d like to see him in some ways get back to at least the theme that basically skyrocketed him to national prominence at the Democratic convention in Boston in 2004, when he talked about blue states, red states and the United States,” Mr. Ornstein said. “That’s not where we are now. We’re blue states and red states. So what do we do? It ought to be a fairly blunt and honest, ‘I failed on that front.’ But if we don’t start to make progress there, it’s a real danger to the future of the country.”

The White House has suggested that Mr. Obama will take an in-your-face tone with congressional Republicans, for example, by leaving an empty seat in the first lady’s guest box to represent victims of gun violence. Partly because it’s the president’s final State of the Union address, Mr. Lehrman said, Mr. Obama “doesn’t have to worry about mincing words.”

“He’s already signaled that he’s taking on Congress by bypassing them on gun control, immigration, inequality, Cuba, maybe closing Guantanamo,” Mr. Lehrman said. “These are all big things he would like to try to get done. He should take on Congress pretty sharply.”

U.S. Chamber of Commerce President Thomas J. Donohue said Monday that he expects Mr. Obama’s final year to be another blitz of excessive regulation. The president set a record with more than 81,700 pages of new and proposed rules to the Federal Register in 2015.

“Six of the seven years of greatest regulatory activity have now taken place on this president’s watch,” Mr. Donohue said in a Chamber op-ed Monday. “And this doesn’t take into account the de facto rules issued as “guidance” or “notice” but are never on the books as official regulations. As the president’s record shows, another 365-plus days of unrelenting regulation by this administration is way too long to go unchecked.”

Although the State of the Union is one of Mr. Obama’s last big opportunities to talk to Americans, most of the country won’t hear him. His annual address to Congress in 2015 drew 31.7 million viewers, the lowest viewership since President Clinton’s final State of the Union address in 2000.

Mr. Obama’s audience in the State of the Union has fallen each year since 2009, when he drew 52.4 million television viewers.